There has been widely known a method of setting an entry prohibited area in view of shapes of machines, tools, jigs, and materials, and the like in advance and performing an interference check using the entry prohibited area to prevent interference of a machine and a tool, a tool and another tool, a tool and a jig, a tool and a material, or other elements during machining according to a machining program in an automatic operation of operating an NC working machine by the machining program to perform machining on a component (an operation of reading the machining program stored in a memory and automatically executing the machining program) (see Patent Document 1 for instance).
Also, there has been proposed a method in which an interference check is performed by simulating a machining program block by block while graphically displaying a machined state of a material by a simulation. Any one of continuation, low-speed switching, and temporary stop of machining is set for a block of the machining program in which an interference error occurs, in a case where a detected interference portion is an entrance allowed area in a real machine. An operation according to the setting is performed if the real machine reaches the interference block during test cutting (see Patent Document 2 for instance).